Figure 5.
BrdU-incorporated neurons persist for several days but eventually die in the damaged brain. A-C, Nissl stain and BrdU immunocytochemistry show that the CA1-hippocampal sector is densely populated by pyknotic (87.3% of total cells; SD, 4.3%) (A, C) and BrdU-positive (81.6% of total cells; SD, 5.1%) (B, C) nuclei in the mice that received a single injection of BrdU (50 mg/kg) on day 2 and were killed on day 7 after hypoxia-ischemia (DAI). D-F, Confocal microscopy analysis reveals extensive colocalization of BrdU (D, F) and TUNEL (E, F) in the condensed nuclei in the CA1-hippocampal subfield, whereas noncondensed BrdU-positive nuclei were TUNEL-negative (D, F, arrows). G-I, BrdU-positive nuclei (G, I) did not colocalize with staining for the mature neuron marker β-tubulin III (H, I), suggesting that BrdU-incorporated cells do not differentiate into mature neurons. J, K, By the 28th day after cerebral hypoxia-ischemia, the damaged CA1-hippocampal subfield is mostly devoid of pyknotic nuclei (J) and not populated by BrdU-positive cells (K) in the mice that received a single injection of BrdU on the 2nd day after the hypoxia-ischemia. Scale bar: A, B, 80 μm; D-I, 60 μm; J, K, 400 μm. DG, Dentate gyrus.